3: Bowel screening (Public Health buzzwords)

Question 1

What is incidence of a disease?

Answer 1

The number of new cases of disease in a population over a certain period of time

Question 2

What is the prevalence of a disease?

Answer 2

The number of cases of the disease present in the population at a certain point in time

Question 3

What is the sensitivity of a test?

Answer 3

Proportion of those WITH the disease who are correctly identified by a POSITIVE RESULT

i.e the ability of a test to correctly identify people who have a disease

Question 4

What is the specificity of a test?

Answer 4

Proportion of those WITHOUT the disease who are correctly identified with a NEGATIVE RESULT

i.e the ability of the test to correctly identify people who don’t have a disease

Question 5

What is the positive predictive value of a test?

Answer 5

Testing true positives / True positives

Question 6

What is the negative predictive value of a test?

Answer 6

Testing true negatives / True negatives

Question 7

What is the yield of a test?

Answer 7

Number of previously undiagnosed people diagnosed with a disease by a screening programme